Field
The described technology generally relates to an organic light-emitting diode (OLED) display.
Description of the Related Technology
An OLED includes two electrodes and an interposed organic light emitting layer. Electrons injected from a cathode electrode and holes injected from an anode electrode are combined in the organic light emitting layer to form excitons. Light is emitted while the excitons discharge energy.
An OLED display includes a matrix of pixels, each including an OLED as well as transistors and capacitors for driving the OLED.
Two types of driving methods are used. An analog driving method is one in which a current is changed to express gray levels and a digital driving method is one in which emitting time is controlled by a switching operation of a driving transistor to express gray levels. For example, in an OLED display employing the digital driving method, it is critical for a driving transistor inside a pixel to stably implement as many subframes in one frame as possible. Thus, the driving transistor can overheat during driving, thereby degrading the organic emission layer. When the heating of the driving transistor becomes excessive, the organic emission layer can deform.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.